PROLONGED STABILITY OF BRAIN NATRIURETIC PEPTIDE - IMPORTANCE FOR NONINVASIVE ASSESSMENT OF CARDIAC-FUNCTION IN CLINICAL-PRACTICE

1. BNP and ANP are important research indices of severity of heart fai lure. However, uncertainty regarding the stability of these peptides a t room temperature has limited their use to assess cardiac function in routine clinical practice. 2. We assessed the stability of BNP and AN P in blood samples left for 2h or 2 days at room temperature compared with levels in blood processed immediately (initial). These times were chosen to reflect possible times for samples to be processed in a hos pital outpatient clinic (2 h) or a blood sample posted to a laboratory from general practice (2 days). Samples were obtained from eight hear t transplant recipients. Blood was separated and plasma stored immedia tely after collection (initial) and after 2 h or 2 days at room temper ature respectively. 3. Initial plasma BNP and ANP values measured by r adioimmunoassay after Sep-Pak extraction were 38.9 +/- 1 1.1(S.E.M.) p g/ml and 113.6+/-28.1 pg/ml, respectively. After 2h at room temperatur e there was no significant fall in either peptide level (35.5+/-9.9pg/ ml, BNP; 104.9 +/- 30.6 pg/ml, ANP). However, after 2 days at room tem perature there was a significant fall in ANP to 38.1 +/- 12.6 pg/ml (P < 0.005 versus initial level). In contrast, there was no significant fall in BN P after 2 days (32.0 +/- 8.4 pg/ml). After 2 days at room t emperature on ly 30.4 +/- 4.3 % of the ANP remained, but 86.0 +/- 5.0% of BNP compared with the initial ANP and BNP measurements. 4. Our stu dy clearly showed that ANP is stable for 2 h and thus could be useful as a screening test for heart disease in hospital. In contrast, BNP re mained stable for 2 days. Measuring BNP may thus be practical as a tes t of heart function both for routine use in hospital and by general pr actitioners in the community.